1. Field of the Invention
The present invention relates to a technique that gives a printing instruction to a printing system in which a plurality of printing apparatuses are series-connected physically (this arrangement will be called tandem-connected printing apparatuses hereinafter), and generates one printed product on one printing medium (the generation of this printed product will be called tandem printing hereinafter).
2. Description of the Related Art
Recently, a spot color expressing a color that cannot be expressed by the process colors or a transparent for giving gloss is often used on the printed product to provide added value to a printed product generated by combining process colors such as CMYK. However, these spot color and transparent can be processed by only a special printing apparatus in most cases. Therefore, printing (to be referred to as added-value printing hereinafter) given an added value is implemented by combining printing apparatuses for performing process color printing, spot color printing, and printing with the transparent toner.
For example, the implementation of added-value printing combining process color printing that performs printing by using CMYK toner or the like and printing with the transparent toner will be explained below. Two printing apparatuses are physically connected in series, and process color printing is performed using the front printing apparatus. After that, the rear printing apparatus performs printing with the transparent toner on the printed product generated by the front printing apparatus. In this printing, the user inputs a print job to the tandem-connected printing apparatuses. On the other hand, a user who does not perform printing with the transparent toner or a user who is satisfied with the image quality of a printed product generated by performing process color printing and printing with the transparent toner by a single printing apparatus inputs a print job to the rear printing apparatus. Thus, the arrangement in which two printing apparatuses each operating as a single printing apparatus as well are tandem-connected can construct printing systems meeting various demands of users.
In the tandem-connected printing apparatuses as described above, a manual insertion paper feed port of the rear printing apparatus is sometimes used as a path to convey a printing medium (a paper sheet or the like) from the front printing apparatus to the rear printing apparatus. In this arrangement, the front printing apparatus closes the manual insertion paper feed port of the rear printing apparatus. This poses the problem that when using the rear printing apparatus as a single printing apparatus, a printing medium having a large grammage such as thick paper or coated paper that can be fed from the manual insertion paper feed unit cannot be fed to the rear printing apparatus.
As a method for avoiding this problem, it is possible to feed a printing medium having a large grammage such as thick paper or coated paper by using a manual insertion paper feed unit of the front printing apparatus. However, this method poses another problem that a fixing portion of the front printing apparatus deteriorates because the printing medium passes through the fixing portion. Furthermore, the printing medium passes through the fixing portions of both the front and rear printing apparatuses. This may give damage to the printing medium, and may make it impossible to obtain a printed product desired by the user.
To solve the above problem, there is a prior art of a printing apparatus including a second conveying path for feeding a continuous sheet fed from a paper feed side toward a paper discharge side by avoiding an image formation unit (fixing portion), in addition to a first conveying path for feeding a continuous sheet having undergone image formation toward to the paper discharge side (Japanese Patent Laid-Open No. 2007-21759).
Unfortunately, the prior art as described above has the problem that the second conveying path that is not used when the printing apparatus operates as a single printing apparatus must be preformed in the printing apparatus, and this unavoidably increases the cost of the printing apparatus.
Also, when inputting a print job to the rear printing apparatus, the user must generate the print job by considering that the manual insertion paper feed unit is physically unusable. When generating a print job, therefore, the user must generate the job by assuming a printing apparatus to which the print job is to be input. This imposes a large burden on the user.